The invention relates to a collector shoe comprising a press-molded main body made of a first carbon material, a layer disposed on a side surface of the main body which is made of a second, less conductive carbon material, and at least one electrical lead imbedded in the collector shoe.
Collector shoes of this type are generally constructed in a single pressing step, in which corresponding layers of the first and second carbon materials in powder form are initially placed in a press mold. The materials are then pressed together with a press die to form a finished collector shoe with an imbedded surface layer. At the same time the press die forces one end of the electric lead into the mass that is being compressed to thereby firmly imbed it therein. In some instances it is necessary that the lead extends from the side of the collector shoe which is covered by the layer of less conductive carbon material. When a collector shoe of this type is produced in the above described conventional manner, the end of the electrical lead must penetrate the surface layer to reach the main body. In so doing it is inevitable that the electrical lead carries some of the second, less conductive carbon material into the first carbon material. This means that some of the second material lodges in an uncontrolled manner between the electric lead and the first carbon material, thereby adversely and in an uncontrolled manner affecting the electrical resistance between the lead and the collector shoe.